Electric vehicle induction machine

ABSTRACT

Provided herein are systems, apparatuses, and methods of providing a centrifugally cast rotor assembly for an induction motor of an electric vehicle. The rotor assembly includes a rotor lamination stack with a cylindrical shape that terminates in a first end surface and a second end surface. The rotor lamination stack has multiple lamination discs, and each lamination disc has multiple rotor slots. The rotor assembly further includes copper bars disposed within the rotor slots, a first intermediary end ring disposed at the first end surface, and a second intermediary end ring disposed at the second end surface. A centrifugally cast first copper end ring that electrically and mechanically couples each of the copper bars is located proximate the first end surface, and a centrifugally cast second copper end ring that electrically and mechanically couples each of the copper bars is located proximate the second end surface.

BACKGROUND

Vehicles such as electric vehicles can obtain power via drive systems.These drive systems can provide power to components of the vehicles.

SUMMARY

At least one aspect is directed to a rotor assembly for an inductionmotor of an electric vehicle. The rotor assembly includes a rotorlamination stack with a cylindrical shape that defines a central axis.The rotor lamination stack terminates in a first end surface and asecond end surface, and a central axial bore extends from the first endsurface to the second end surface. The rotor lamination stack hasmultiple lamination discs. Each lamination disc has multiple rotorslots. The rotor assembly further includes copper bars disposed withinthe rotor slots. Each of the copper bars extends beyond the first endsurface of the rotor lamination stack and beyond the second end surfaceof the rotor lamination stack. The rotor assembly further includes afirst intermediary end ring disposed at the first end surface of therotor lamination stack, and a second intermediary end ring disposed atthe second end surface of the rotor lamination stack. The rotor assemblyfurther includes a centrifugally cast first copper end ring thatelectrically and mechanically couples each of the copper bars proximatethe first end surface of the rotor lamination stack and a centrifugallycast second copper end ring that electrically and mechanically coupleseach of the copper bars proximate the second end surface of the rotorlamination stack. Each of the centrifugally cast first copper end ringand the centrifugally cast second copper end ring can be centrifugallycasted with the copper bars are inserted into the rotor slots.

At least one aspect is directed to a method. The method can includeproviding centrifugally cast copper rotor assemblies for inductionmotors of electric vehicles. The method can include stacking multiplelamination discs to form a rotor core assembly with a cylindrical shapedefining a central axis. The rotor core assembly has a first end, asecond end, and a central axial bore extending from the first end to thesecond end. Each of the lamination discs can include multiple rotorslots. The method can include positioning an inner die component and anouter die component at the first end of the rotor core assembly to forma casting material cavity. The method can include inserting copper barsinto the rotor slots. Each copper bar extends beyond a first end surfaceand a second end surface of the rotor core assembly. The method furtherincludes rotating the rotor core assembly about the central axis andpouring molten copper through the central axial bore and into thecasting material cavity to form a first copper cast end ring thatelectrically and mechanically couples each copper bar proximate thefirst end of the rotor core assembly.

At least one aspect is directed to an electric vehicle. The electricvehicle can include an induction motor to drive the electric vehicle.The induction motor can include a motor shaft, a stator assembly, and arotor assembly. The rotor assembly includes a rotor lamination stackwith a cylindrical shape that defines a central axis. The rotorlamination stack terminates in a first end surface and a second endsurface, and a central axial bore extends from the first end surface tothe second end surface. The rotor lamination stack has multiplelamination discs. Each lamination disc has multiple rotor slots. Therotor assembly further includes copper bars disposed within the rotorslots. Each of the copper bars extends beyond the first end surface ofthe rotor lamination stack and beyond the second end surface of therotor lamination stack. The rotor assembly further includes a firstintermediary end ring disposed at the first end surface of the rotorlamination stack, and a second intermediary end ring disposed at thesecond end surface of the rotor lamination stack. The rotor assemblyfurther includes a centrifugally cast first copper end ring thatelectrically and mechanically couples each of the copper bars proximatethe first end surface of the rotor lamination stack and a centrifugallycast second copper end ring that electrically and mechanically coupleseach of the copper bars proximate the second end surface of the rotorlamination stack. Each of the centrifugally cast first copper end ringand the centrifugally cast second copper end ring is formed using acentrifugal casting process after the copper bars are inserted into therotor slots.

At least one aspect is directed to an apparatus to centrifugally castcopper rotor assemblies for induction motors of electric vehicles. Theapparatus can include a rotor assembly. The rotor assembly can have acylindrical shape that defines a central axis. The rotor assembly canterminate in a first end and a second end. The apparatus can furtherinclude an inner die component and an outer die component. Each of theinner die component and the outer die component can be disposed at thefirst end of the rotor assembly. The apparatus can include a spinnerassembly. The spinner assembly can include a lower structure, an upperstructure, and a sidewall structure. The lower structure can be disposedbeneath the rotor assembly and can include a base plate, a spindlecomponent configured to mate with the outer die component, and a firstbearing assembly. The first bearing assembly can include a first innerring component and a first outer ring component. The first outer ringcomponent can be fixedly coupled with the base plate and the first innerring component can be fixedly coupled with the spindle component suchthat the spindle component is permitted to rotate with the rotorassembly about the central axis relative to the base plate. The upperstructure can be disposed above the rotor assembly and can include anupper plate, a drive wheel component configured to mate with the rotorassembly, and a second bearing assembly. The second bearing assembly caninclude a second inner ring component and a second outer ring component.The second outer ring component can be fixedly coupled with the upperplate and the second inner ring component can be fixedly coupled withthe drive wheel component such that the drive wheel component ispermitted to rotate with the rotor assembly about the central axisrelative to the upper plate. The sidewall structure can couple the lowerstructure to the upper structure. The apparatus can further include amotor that can drive rotation of the drive wheel component.

At least one aspect is directed to a spinner assembly of a centrifugalcasting process of a rotor assembly used in an induction motor of anelectric vehicle. The spinner assembly can include a lower structure, anupper structure, and a sidewall structure. The lower structure can bedisposed beneath the rotor assembly and can include a base plate, aspindle component configured to mate with the outer die component, and afirst bearing assembly. The first bearing assembly can include a firstinner ring component and a first outer ring component. The first outerring component can be fixedly coupled with the base plate and the firstinner ring component can be fixedly coupled with the spindle componentsuch that the spindle component is permitted to rotate with the rotorassembly about the central axis relative to the base plate. The upperstructure can be disposed above the rotor assembly and can include anupper plate, a drive wheel component configured to mate with the rotorassembly, and a second bearing assembly. The second bearing assembly caninclude a second inner ring component and a second outer ring component.The second outer ring component can be fixedly coupled with the upperplate and the second inner ring component can be fixedly coupled withthe drive wheel component such that the drive wheel component ispermitted to rotate with the rotor assembly about the central axisrelative to the upper plate. The sidewall structure can couple the lowerstructure to the upper structure.

At least one aspect is directed to a method. The method can includeproviding a rotor assembly with a cylindrical shape that defines acentral axis. The rotor assembly can terminate in a first end and asecond end. The method can include providing an inner die component, andproviding an outer die component. Each of the inner die component andthe outer die component can be disposed at the first end of the rotorassembly. The method can include providing a spinner assembly. Thespinner assembly can include a lower structure, an upper structure, anda sidewall structure. The lower structure can be disposed beneath therotor assembly and can include a base plate, a spindle componentconfigured to mate with the outer die component, and a first bearingassembly. The first bearing assembly can include a first inner ringcomponent and a first outer ring component. The first outer ringcomponent can be fixedly coupled with the base plate and the first innerring component can be fixedly coupled with the spindle component suchthat the spindle component is permitted to rotate with the rotorassembly about the central axis relative to the base plate. The upperstructure can be disposed above the rotor assembly and can include anupper plate, a drive wheel component configured to mate with the rotorassembly, and a second bearing assembly. The second bearing assembly caninclude a second inner ring component and a second outer ring component.The second outer ring component can be fixedly coupled with the upperplate and the second inner ring component can be fixedly coupled withthe drive wheel component such that the drive wheel component ispermitted to rotate with the rotor assembly about the central axisrelative to the upper plate. The sidewall structure can couple the lowerstructure to the upper structure. The method can further includeproviding a motor that drive rotation of the drive wheel component.

At least one aspect is directed to a method. The method can includeproviding a spinner assembly. The spinner assembly can include a lowerstructure, an upper structure, and a sidewall structure. The lowerstructure can be disposed beneath the rotor assembly and can include abase plate, a spindle component configured to mate with the outer diecomponent, and a first bearing assembly. The first bearing assembly caninclude a first inner ring component and a first outer ring component.The first outer ring component can be fixedly coupled with the baseplate and the first inner ring component can be fixedly coupled with thespindle component such that the spindle component is permitted to rotatewith the rotor assembly about the central axis relative to the baseplate. The upper structure can be disposed above the rotor assembly andcan include an upper plate, a drive wheel component configured to matewith the rotor assembly, and a second bearing assembly. The secondbearing assembly can include a second inner ring component and a secondouter ring component. The second outer ring component can be fixedlycoupled with the upper plate and the second inner ring component can befixedly coupled with the drive wheel component such that the drive wheelcomponent is permitted to rotate with the rotor assembly about thecentral axis relative to the upper plate. The sidewall structure cancouple the lower structure to the upper structure.

These and other aspects and implementations are discussed in detailbelow. The foregoing information and the following detailed descriptioninclude illustrative examples of various aspects and implementations,and provide an overview or framework for understanding the nature andcharacter of the claimed aspects and implementations. The drawingsprovide illustration and a further understanding of the various aspectsand implementations, and are incorporated in and constitute a part ofthis specification.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings are not intended to be drawn to scale. Likereference numbers and designations in the various drawings indicate likeelements. For purposes of clarity, not every component can be labeled inevery drawing. In the drawings:

FIG. 1 depicts an isometric view of an example centrifugally cast copperrotor assembly of an induction motor in an electric vehicle;

FIG. 2 depicts an exploded isometric view of an example centrifugallycast copper rotor assembly of an induction motor in an electric vehicle;

FIG. 3 depicts an isometric view of an example centrifugally cast copperend ring for a rotor assembly of an induction motor in an electricvehicle;

FIG. 4 depicts an isometric view of an example centrifugally cast copperend ring for a rotor assembly of an induction motor in an electricvehicle;

FIG. 5 depicts an isometric view of an example centrifugally cast copperrotor assembly of an induction motor in an electric vehicle;

FIG. 6 depicts an exploded perspective, isometric view of an examplecentrifugally cast copper rotor assembly of an induction motor in anelectric vehicle;

FIG. 7 depicts an isometric view of an example centrifugally cast copperend ring for a rotor assembly of an induction motor in an electricvehicle;

FIG. 8 depicts an isometric view of an example centrifugally cast copperend ring for a rotor assembly of an induction motor in an electricvehicle;

FIG. 9 depicts an isometric view of an example centrifugal castingapparatus for a rotor assembly of an induction motor in an electricvehicle;

FIG. 10 depicts a side elevation view of an example centrifugal castingapparatus for a rotor assembly of an induction motor in an electricvehicle;

FIG. 11 depicts an isometric view of an example centrifugal castingapparatus for a rotor assembly of an induction motor in an electricvehicle;

FIG. 12 depicts an isometric view of an example spinner assembly thatcan be used in a centrifugal casting apparatus for a rotor assembly ofan induction motor in an electric vehicle;

FIG. 13 depicts a side cross-sectional view of an example spinnerassembly that can be used in a centrifugal casting apparatus for a rotorassembly of an induction motor in an electric vehicle;

FIG. 14 depicts an exploded isometric view of an example rotor assemblyof an induction motor in an electric vehicle;

FIG. 15 depicts an isometric view of an example rotor assembly of aninduction motor in an electric vehicle;

FIG. 16 depicts a top elevation view of an example lamination stackassembly used in a rotor assembly of an induction motor in an electricvehicle;

FIG. 17 depicts a detail elevation view of an example lamination stackrotor slot used in a rotor assembly of an induction motor in an electricvehicle;

FIG. 18 depicts a side cross-sectional view of an example laminationstack assembly used in a rotor assembly of an induction motor in anelectric vehicle;

FIG. 19 depicts an isometric view of an example inner die component usedin a centrifugal casting apparatus for a rotor assembly of an inductionmotor in an electric vehicle;

FIG. 20 depicts an isometric view of an example inner die component usedin a centrifugal casting apparatus for a rotor assembly of an inductionmotor in an electric vehicle;

FIG. 21 depicts an isometric view of an example outer die component usedin a centrifugal casting apparatus for a rotor assembly of an inductionmotor in an electric vehicle;

FIG. 22 depicts an isometric view of an example outer die component usedin a centrifugal casting apparatus for a rotor assembly of an inductionmotor in an electric vehicle;

FIG. 23 depicts a block diagram of a cross-sectional view of an exampleelectric vehicle installed with an induction motor;

FIG. 24 depicts a flow diagram of an example method for initiating acentrifugal casting process for a rotor assembly of an induction motorin an electric vehicle;

FIG. 25 depicts a flow diagram of an example method for centrifugallycasting a rotor assembly of an induction motor in an electric vehicle;

FIG. 26 depicts a flow diagram of an example method of providing aninduction motor for an electric vehicle;

FIG. 27 depicts a flow diagram of an example method of providing acentrifugally cast copper rotor assembly of an induction motor in anelectric vehicle;

FIG. 28 depicts a flow diagram of an example method of providing anapparatus to centrifugally cast a copper rotor assembly of an inductionmotor in an electric vehicle;

FIG. 29 depicts a flow diagram of an example method of providing aspinner assembly for use in the centrifugal casting process of a copperrotor assembly of an induction motor in an electric vehicle.

DETAILED DESCRIPTION

Following below are more detailed descriptions of various conceptsrelated to, and implementations of a centrifugal casting process for therotor assemblies of induction motors of electric vehicles. The variousconcepts introduced above and discussed in greater detail below can beimplemented in any of numerous ways.

Systems and methods described herein relate to a centrifugally castrotor assembly of an induction motor for an electric vehicle. Electricvehicles can include DC motors or AC induction motors to achieve thevariable levels of speed and torque required to drive a vehicle. ACinduction motors can deliver the performance provided by DC motors aswell as the additional benefits associated with AC induction motors,including small size, low cost, high reliability and low maintenance.

Induction motors can include a rotor assembly that rotates relative to astator assembly. Aluminum or copper can be used to fabricate a squirrelcage structure within the rotor assembly. The aluminum and the copperutilized in the rotor assemblies can be in either pure or alloy form.Aluminum rotors have lower conductivity and lower efficiency than copperrotors. However, copper rotors can be difficult to manufacture. Forexample, copper rotors manufactured using vacuum or induction brazingmethods can suffer from strength and reliability issues when implementedin high speed rotation applications. Similarly, copper rotorsmanufactured using gravity casting methods can suffer from quality andprocess issues, for example, high porosity of cast material. Inaddition, the high temperature required by gravity casting can damagethe iron core materials of the rotor, resulting in higher electricallosses and motor performance degradation.

In one aspect, the problem of manufacturing copper rotors can beaddressed herein by utilizing a centrifugal casting process. Centrifugalcasting provides several advantages over other fabrication methods. Thecentrifugal casting process is simple and yields high structural qualityend rings with good dimensional size control, low porosity, and finecopper grain sizes. The rotor has high structural strength because thecopper bars of the squirrel cage can be pre-fabricated, and only the endrings are formed during the casting process. The centrifugal castingprocess is well-suited for rotor designs with small and narrow rotorslots, and the rotor has high durability because the casting processforms a good joining interface for the copper bars.

The induction motors described herein are for an automotiveconfiguration. An automotive configuration includes a configuration,arrangement or network of electrical, electronic, mechanical orelectromechanical devices within a vehicle of any type. An automotiveconfiguration can include induction motors for use in electric vehicles(EVs). EVs can include electric automobiles, hybrid automobiles, cars,motorcycles, scooters, passenger vehicles, passenger or commercialtrucks, and other vehicles such as sea or air transport vehicles,planes, helicopters, submarines, boats, or drones. EVs can be fullyautonomous, partially autonomous, or unmanned.

FIGS. 1 and 2, among others, respectively depict isometric and explodedisometric views of a centrifugally cast copper rotor assembly 100. Thecentrifugally cast copper rotor assembly 100 can be part of an inductionmotor that provides the speed and torque required to drive an electricvehicle. The views of FIGS. 1 and 2 do not depict every component of theinduction motor. For example, FIGS. 1 and 2 do not show the motor shaft,the stator assembly, or the bearing assemblies of the induction motor.Specifically referring to FIG. 2, although the exploded view presentsthe components of the rotor assembly 100 as separable, after thecentrifugal casting process has been completed, the components can beinseparable as described herein.

The rotor assembly 100 can include a first centrifugally cast copper endring 105, a first intermediary ring 120, a rotor lamination stack 115, asecond intermediary end ring 125, and a second centrifugally cast copperend ring 110. The first centrifugally cast copper end ring 105, thefirst intermediary ring 120, the rotor lamination stack 115, the secondintermediary end ring 125, and the second centrifugally cast copper endring 110 can be arranged in that order to form the cylindrical shape ofthe rotor assembly 100. In some instances, the rotor assembly 100 doesnot include the first intermediary ring 120 and the second intermediaryring 125. In some other instances, a cross-section of the rotor assembly100 can be other than circular, and can instead be oval, elliptical,rectangular, or any other shape.

Rotor lamination stack 115 can include a plurality of lamination discsdisposed on top of each other to form a cylindrical shape that defines acentral axis 106. The cylindrical shape of the rotor lamination stack115 extends from a first end surface 112 proximate a first end 101 to asecond end surface 118 proximate a second end 103. The rotor laminationstack 115 can include a range from 100 to 1200 individual laminationdiscs. Each of the lamination discs can be fabricated from electricsteel with a thickness between 0.18 mm and 0.40 mm. Each disc can beformed using a stamping process or any other suitable fabricationtechnique. For example, each disc can include multiple rotor slotsstamped about the outer perimeter of the disc. Each slot can permit theinsertion of a copper bar 130. In some instances, each disc is coatedwith an oxide in order to electrically insulate the metal discs from oneanother. Alternatively, in some other instances, the discs comprisingthe rotor lamination stack can be electrically isolated from one anotherby the inclusion of an electrically insulating spacer disc locatedbetween adjacent metal discs.

The first intermediary end ring 120 can be arranged such that aninterior (i.e., opposite the end ring 105) surface of the intermediaryend ring 120 contacts the first end surface 112 of the rotor laminationstack 115. Similarly, the second intermediary end ring 125 can bearranged such that an interior (i.e., opposite the end ring 110) surfaceof the intermediary end ring 125 contacts the second end surface 118 ofthe rotor lamination stack 115. In some instances, each of the firstintermediary end ring 120 and the second intermediary end ring 125 isfabricated from stainless steel or electric steel with a thicknessranging from 1 mm to 5 mm. The width of each of the first intermediaryend ring 120 and the second intermediary end ring 125 can besubstantially identical (±10%) as the width of the rotor laminationstack 115.

Each of the first intermediary end ring 120 and the second intermediaryend ring 125 can include multiple rotor slots. In some instances, therotor slots of the first intermediary end ring 120 and the secondintermediary end ring 125 can be slightly larger than the rotor slots ofthe lamination discs, for example, the width of the rotor slots of thefirst intermediary end ring 120 and the second intermediary end ring 125can be 5% larger than the rotor slots of the lamination discs. The rotorslots of the intermediary end rings 120, 125 are intended to align withthe rotor slots of the rotor lamination stack 115. In this way, multiplecopper bars 130 can be arranged to pass through the first intermediaryend ring 120, the rotor lamination stack 115, and the secondintermediary end ring 125. For example, in a fully installedconfiguration, each copper bar 130 can extend a length ranging from 20mm to 50 mm past the first end surface 112. In some instances, eachcopper bar 130 extends an equal length past the second end surface 118in the fully installed configuration. In other instances, each copperbar 130 extends an unequal length past the second end surface 118 in thefully installed configuration.

Each copper bar 130 can have a bar length ranging from 80 mm to 300 mm,a bar height ranging from 10 mm to 25 mm, and a bar width of 3 mm to 15mm. In some instances, the copper bars 130 are fabricated fromoxygen-free electrolytic copper, which can also be referred to as OFE orC10100 copper. OFE copper, which has the highest purity for standardizedcopper, has a purity grade of 99.99%. As such, it is extremelyhomogenous, exhibits high thermal and electrical conductivity, and isimmune to hydrogen embrittlement. The use of OFE copper bars that arefabricated (e.g., machined) prior to the casting process ensures thatthe rotor assembly is robust since the use of cast copper bars 130 canresult in defects and impurities that can degrade the performance of therotor. In addition, the pre-insertion of the copper bars 130 into therotor slots of the rotor lamination stack 115 prior to the initiation ofthe centrifugal casting process can prevent the molten copper used inthe casting process from flowing into the rotor slots of the laminationdiscs of the rotor lamination stack 115, preventing damage to thelamination discs.

FIGS. 3 and 4, among others, depict isometric views of a firstcentrifugally cast copper end ring 105 for a rotor assembly 100 of aninduction motor in an electric vehicle. Although FIGS. 3 and 4specifically depict the first end ring 105, all of the descriptionincluded below is equally applicable to the second end ring 110. Withreference to FIG. 2, although FIGS. 3 and 4 depict end rings 105, 110 asseparable from the copper bars 130 of the rotor assembly 100, after thecentrifugal casting process has been completed, the end rings 105, 110can be inseparable from the copper bars 130.

The first centrifugally cast copper end ring 105 can be a ring-shapedstructure with an exterior face 135, an interior face 140, an outercircumferential face 145, and an inner circumferential face 150. Whenincluded as part of the rotor assembly 100, the exterior face 135 can beoriented away from the rotor lamination stack 115, while the interiorface 140 can be oriented towards the rotor lamination stack 115. Theouter circumferential face 145 can have an outer diameter ranging from120 mm to 300 mm, while the inner circumferential face 150 can have aninner diameter ranging from 60 mm to 260 mm.

The interior face 140 of the first end ring 105 can include multiplerecesses 155 distributed about the interior face 140 near the outercircumferential face 145. The recesses 155 can be formed when castcopper flows and solidifies around the copper bars 130 during thecentrifugal casting process. In addition to mechanically andelectrically coupling with the copper bars 130, the interior face 140 ofthe first end ring 105 can contact an exterior surface of the firstintermediary end ring 120.

FIGS. 5 and 6, among others, respectively depict isometric and explodedisometric views of another example centrifugally cast copper rotorassembly 500. The centrifugally cast rotor assembly 500 can be part ofan induction motor that provides the speed and torque required to drivean electric vehicle. The views of FIGS. 5 and 6 do not depict everycomponent of the induction motor. For example, FIGS. 5 and 6 do not showthe rotor shaft, the stator assembly, or the bearing assemblies of theinduction motor. Referring to FIG. 6, among others, although theexploded view presents the components of the rotor assembly 500 asseparable, after the centrifugal casting process has been completed, thecomponents can be inseparable as described herein.

The rotor assembly 500 can include a first centrifugally cast copper endring 505, the first intermediary ring 120, the rotor lamination stack115, the second intermediary ring 125, and a second centrifugally castcopper end ring 510. Copper bars 130 can be inserted through slotsdisposed in the first intermediary ring 120, the rotor lamination stack115, and the second intermediary ring 125. In contrast to the rotorassembly 100 depicted in FIGS. 1-4, each of the first end ring 505 andthe second end ring 510 can include multiple cooling fin featuresdesigned to more efficiently transfer heat from the end rings 505 and510 than the end rings 105 and 110 of rotor assembly 100.

FIGS. 7 and 8, among others, depict isometric views of a firstcentrifugally cast copper end ring 505 for a rotor assembly 500 of aninduction motor in an electric vehicle. Although FIGS. 7 and 8specifically depict the first end ring 505, all of the descriptionincluded below is equally applicable to the second end ring 510. It isalso important to note that although FIGS. 6-8 depict end rings 505, 510as separable from the copper bars 130 of the rotor assembly 500, afterthe centrifugal casting process has been completed, the end rings 505,510 are inseparable from the copper bars 130.

The first centrifugally cast copper end ring 505 can be a ring-shapedstructure with an exterior face 535, an interior face 540, an outercircumferential face 545, and an inner circumferential face 550. Whenincluded as part of the rotor assembly 500, the exterior face 535 can beoriented away from the rotor lamination stack 115, while the interiorface 540 can be oriented towards the rotor lamination stack 115. Theouter circumferential face 545 can have an outer diameter ranging from120 mm to 300 mm, while the inner circumferential face 550 can have aninner diameter ranging from 60 mm to 260 mm.

The interior face 540 of the first end ring 505 can include multiplerecesses 555 distributed about the interior face 540 near the outercircumferential face 545. The recesses 555 can be formed when castcopper flows and solidifies around the copper bars 130 during thecentrifugal casting process. In addition to mechanically andelectrically coupling with the copper bars 130, the interior face 540 ofthe first end ring 505 can contact an exterior surface of the firstintermediary end ring 120.

The first centrifugally cast copper end ring 505 can also includemultiple cooling fins 560 distributed about the inner circumferentialface 550. Each of the cooling fins 560 can extend radially inward to thecenter of the ring 505, although the cooling fins 560 can be oriented inany suitable direction. The length the cooling fins 560 extend from theinner circumferential face 550 can range from 5 mm to 60 mm, and can beselected based on an amount of desired heat transfer from the end ring505. In some instances, the cooling fins 560 have a rectangular shapewith rounded edges, although any other suitable geometry can beutilized.

FIGS. 9 and 10, among others, respectively depict isometric and sideviews of a centrifugal casting apparatus 900. Preferably, thecentrifugal casting apparatus 900 is used to fabricate the end rings ofa rotor assembly in which the conductive bars and the end rings areconstructed from pure copper or a copper-containing material, althoughthis technique may also be used to fabricate rotor assemblies comprisedof other materials (e.g., aluminum).

Centrifugal casting apparatus 900 can include a spinner assembly 905 anda driven motor assembly 910. The motor assembly 910 can be used to driverotation of certain components of the spinner assembly 905 to supply thecentrifugal force required to cast the copper and form the end rings.The drive torque provided by the motor assembly 910 can range from 50N-m to 300 N-m depending on the size of the spinner assembly 905 and therotor assembly to be casted. In an example instance, the motor assembly910 can be coupled with the spinner assembly 905 using a drive belt 915.The drive belt 915 can be any suitable style of belt, including, but notlimited to, a V-belt, a multi-groove belt, a ribbed belt, or a timingbelt. In other instances, a chain, pulley, or gear drive system can beutilized to couple the spinner assembly 905 to the motor assembly 910.In some other instances, the spinner assembly 905 and the motor assembly910 can be situated such that a direct drive connection is utilized totransfer a drive torque from the motor assembly 910 to the spinnerassembly 905.

The spinner assembly 905 and the motor assembly 910 can be secured to acasting support structure 945. The casting support structure 945 can bea table-like apparatus with a substantially horizontal support componentand multiple legs extending vertically from the horizontal supportcomponent. For example, the spinner assembly 905 can be secured (i.e.,by mechanical fasteners, welding) to the horizontal support component.The horizontal support component can further include a recess configuredto permit a portion of the motor assembly 910 to pass through thehorizontal support component. In this way, the spinner assembly 905 andthe motor assembly are aligned such that the drive belt 915 issubstantially (i.e., ±10°) horizontal. In some instances, the spinnerassembly 905 and the motor assembly 910 are disposed side-by-side. Insome other instances, the spinner assembly 905 and the motor assembly910 are disposed in any orientation relative to each other (i.e., themotor assembly 910 disposed above or below the spinner assembly 905)that permits the efficient transfer of drive torque from the motorassembly 910 to the spinner assembly 905.

Anti-oxidation shield 925 can at least partially encapsulate the spinnerassembly 905, the motor assembly 910, and the casting support structure945 during a centrifugal casting process. As used herein, “partiallyencapsulate” can refer to a majority of the volume occupied by each ofthe components 905, 910, 945 located within the anti-oxidation shield925, without the creation of a hermetic seal. Anti-oxidation shield 925can include a main body portion 930, an anti-oxidation gas inlet 935 andan anti-oxidation gas outlet 940. Each of the main body portion 930, theinlet 935, and the outlet 940 can be fabricated from a non-reactivehigh-temperature plastic material or sheet metal (e.g., aluminum,stainless steel). During the centrifugal casting process, molten coppercan interact with atmospheric oxygen, resulting in an oxidationreaction. The rate of oxidation can increase with temperature. Theoxidation reaction can cause an oxide skin to form on the surface of themolten copper during the melting process, which can become trapped inthe bulk of the molten copper and transferred to the finished cast endrings. Inclusion of the oxide skin into the finished cast end rings canlead to defects and discontinuities that degrade the mechanical andelectrical performance of the finished product.

The main body portion 930 of the anti-oxidation shield 925 can be usedto direct and contain a gas with anti-oxidation properties in the areasurrounding the spinner assembly 905, which can result in a reduction inthe formation of an oxide skin in the molten copper used in the castingprocess. Specifically referring to FIG. 10, the main body portion 930can include multiple sidewalls 955 coupled with a top wall 960 to form abox-like structure. In other instances, the main body portion 930 canhave a different shape (e.g., a tube shape, a semi-circular shape). Thetop wall 960 can further include a sprue passage hole 963 to permit thepassage of the sprue gate 920 through the anti-oxidation shield 925 sothat molten copper can be supplied to the spinner assembly 905. Thediameter of the sprue passage hole 963 can be selected to permit passageof the sprue gate 920 without permitting a significant volume of theanti-oxidation gas to escape from the main body portion 930.

The gas inlet 935 can be fluidly coupled (e.g., by a tube connection) toa source of anti-oxidizing gas, while the gas outlet 940 can be fluidlycoupled with an exhaust system. The anti-oxidizing gas can becontinuously flowing through the anti-oxidation shield 925 during thecasting process. In some example instances, the anti-oxidation gas ispure nitrogen, or a nitrogen-containing mixture. In other exampleinstances, the gas is either a pure gas or a mixture containing one ofthe following: argon, chlorine, Freon, or hexachloroethane.

FIG. 11, among others, depicts an isometric view of the centrifugalcasting apparatus 900 with the anti-oxidation shield 925 removed fromthe apparatus. In an example instance, the centrifugal casting apparatus900 can be utilized to complete a copper centrifugal casting processwithout the use of anti-oxidation shield 925. Motor assembly 910 can besecured to the casting support structure 945 through use of a motorsupport structure 950. In some instances, the motor support structure950 includes a collar structure that wraps around the motor and issecured (e.g., by mechanical fasteners, welding) to an L-shapedstructure. The L-shaped structure can be secured to the casting supportstructure 945 using any suitable method (e.g., mechanical fasteners,welding) to secure and maintain the motor in a position such that thedrive belt 915 is substantially horizontal (i.e., parallel to the topsurface of the casting support structure 945).

The motor assembly 910 can further include a drive wheel 965. The drivewheel 965 can be secured to a drive shaft of the motor (e.g., using abolted connection) such that rotation of the drive shaft causes acorresponding rotation of the drive wheel 965. The outer diameter of thedrive wheel 965 (i.e., the portion of the drive wheel 965 contacting thedrive belt 915) can be selected, along with the drive speed of themotor, to achieve a targeted rotational speed of the spinner assembly.For example, the outer diameter of the drive wheel 965 can range from200 mm to 500 mm. The height of the drive wheel 965 can similarly beselected to accommodate the height of the drive belt 915. For example,the height of the drive wheel 965 can range from 20 mm to 80 mm. Theproperties of the drive belt 915 (e.g., height, thickness, material) canbe selected to withstand the torque provided by the motor assembly andthe heat of the casting process. In other example instances, thecentrifugal casting assembly 900 can include a chain or gear drivesystem. In these instances, the drive wheel 965 can alternatively bereplaced by a sprocket component or a gear component.

FIGS. 12 and 13, among others, respectively depict isometric and sidecross-sectional views of the spinner assembly 905. Spinner assembly 905can include, among other components, a base plate assembly 1205, asidewall structure 1210, an upper plate assembly 1230, and a drive wheelassembly 1250. Any or all of the components of the spinner assembly 905can be fabricated from a material with good strength and heat-resistanceproperties (e.g., stainless steel).

Base plate assembly 1205 can include a base plate 1300, a spindlecomponent 1305, and a bearing assembly 1310. Base plate 1300 can have acircular shape with multiple mounting holes 1301 distributed about theouter periphery of the base plate 1300. For example, mounting holes 1301can be countersunk holes. Fasteners (e.g., bolts, pins) can pass throughthe mounting holes 1301 in order to couple the base plate assembly 1205to the sidewall structure 1210. In some embodiments, the base plateassembly 1205 can be inseparably coupled with the sidewall structure1210 using another method of joining components (e.g., welding, spotwelding, brazing, metal gluing, riveting).

As shown specifically in FIG. 13, the thickness of base plate 1300 canbe substantially uniform (i.e., ±5 mm) with thicker regions located atthe outer periphery near the mounting holes 1301 and near the centersurrounding the spindle component 1305 and the bearing assembly 1310.For example, the base plate 1300 can have a nominal thickness rangingfrom 20 mm to 100 mm, and a maximum thickness ranging from 100 mm to 300mm in the region of the spindle component 1305.

The spindle component 1305 can be fabricated from stainless steel or anyother suitable material as a solid component. The spindle component 1305can include mating features (e.g., a cone-shaped protrusion) that permitthe spindle component 1305 to mate with an outer die component (e.g.,outer die component 1340) of the centrifugal casting apparatus 900 suchthat rotation of the outer die component causes a corresponding rotationto the spindle component 1305. The bearing assembly 1310 can be any typeof mechanical bearing assembly (e.g., a ball bearing assembly, a rollerbearing assembly) with an inner ring component 1313, an outer ringcomponent 1316, and rolling components (e.g., balls) contained betweenthe inner ring component 1313 and the outer ring component 1316. Theouter ring component 1316 can be fixedly coupled with the base plate1300, while the inner ring component 1313 can be fixedly coupled withthe spindle component 1305 such that the inner ring component 1313 andthe spindle component 1305 can rotate freely relative to the outer ringcomponent 1316.

Referring again to FIG. 12, the sidewall structure 1210 can include alower cylindrical portion 1215, a first upper portion 1220, and a secondupper portion 1225. The lower cylindrical portion 1215 can be aring-shaped structure. The height of the lower cylindrical portion 1215can be selected such that the die components of the centrifugal castingassembly (e.g., the outer die component 1340 and the inner die component1345) are located within the volume bounded by the lower cylindricalportion 1215 when a rotor assembly 1200 is installed in the spinnerassembly 905. For example, the height of the lower cylindrical portion1215 can range from 200 mm to 800 mm. The outer diameter of the lowercylindrical portion 1215 can be selected to permit sufficient clearanceabout the outer die component 1340. For example, the outer diameter ofthe lower cylindrical portion 1215 can range from 500 mm to 1200 mm.Each of the portions 1215, 1220, 1225 of the sidewall structure 1210 canbe a uniform thickness. For example, the thickness of the sidewallstructure 1210 can range from 15 mm to 50 mm.

The upper plate assembly 1230 can include a central ring portion 1235, afirst arm portion 1240, and a second arm portion 1245. The central ringportion 1235 can be a ring-shaped member disposed beneath a portion ofthe drive wheel assembly 1250. First arm portion 1240 extends in a firstdirection away from the central ring portion 1235, while second armportion 1245 extends from the central ring portion 1235 in a seconddirection. In an example instance, the first direction and the seconddirection are spaced opposite each other (i.e., 180° apart). Both thefirst arm portion 1240 and the second arm portion 1245 can includemultiple holes to permit the passage of fasteners (e.g., bolts, pins,screws) to secure the first arm portion 1240 to the first upper portion1220 and the second arm portion 1245 to the second upper portion 1225.

Each of the first arm portion 1240 and the second arm portion 1245 caninclude rectangular-shaped cutout regions. In other instances, thecutout regions can have any other desired shape (e.g., circle, square,oval). The cutout regions can reduce the weight of the upper plateassembly 1230. Reduction of the weight of the upper plate assembly 1230can be desirable as the centrifugal casting process can include multiplesteps of coupling and decoupling the upper plate assembly 1230 from thesidewall structure 1210 in order to position the rotor assembly 1200.

As shown specifically in FIG. 13, the thickness of the central ringportion 1235, the first arm portion 1240, and the second arm portion1245 can be substantially uniform (i.e., ±5 mm) with thicker regionslocated at the outer periphery near the upper portions 1220, 1225 andnear the center surrounding the bearing assembly 1315 and the drivewheel assembly 1250. For example, the central ring portion 1235, thefirst arm portion 1240, and the second arm portion 1245 can have anominal thickness ranging from 15 mm to 30 mm. The central ring portion1235 can have a maximum thickness ranging from 50 mm to 150 mm in theregion of the bearing assembly 1315.

The bearing assembly 1315 can be any type of mechanical bearing assembly(e.g., a ball bearing assembly, a roller bearing assembly) with an innerring component 1318, an outer ring component 1321, and rollingcomponents (e.g., balls) contained between the inner ring component 1318and the outer ring component 1321. The outer ring component 1321 can befixedly coupled with the central ring portion 1235, while the inner ringcomponent 1318 can be fixedly coupled with an inner drive wheelcomponent 1325 of the drive wheel assembly 1250 such that the inner ringcomponent 1318 of the bearing assembly 1315, the inner drive wheelcomponent 1325 of the drive wheel assembly 1250, and the outer drivewheel component 1320 of the drive wheel assembly 1250 can rotate freelyrelative to the outer ring component 1321 of the bearing assembly 1315.

The outer drive wheel component 1320 can be a ring-shaped member withmultiple teeth or grooves running either continuously ornon-continuously on an exterior circumferential surface of the member.The geometry of the teeth or grooves (e.g., number of teeth or grooves,depth, width) can be selected to accommodate the properties of the drivebelt 915. For example, the drive belt 915 can include two or moregrooves that mesh with the teeth of the outer drive wheel component 1320such that power from the drive belt 915 is transmitted to the outerdrive wheel component 1320, resulting in the rotation of the outer drivewheel component 1320. Similarly, the height of the outer drive wheelcomponent 1320 can be selected to accommodate the height of the drivebelt 915. For example, the height of the outer drive wheel component1320 can range from 20 mm to 80 mm. In other example instances, thecentrifugal casting apparatus 900 can include a chain or gear drive, anda sprocket component or a gear component can be used in place of theouter drive wheel component 1320.

The inner drive wheel component 1325 can be coupled with the outer drivewheel component 1320 such that rotation of the outer drive wheelcomponent 1320 due to power transmission from the drive belt 915 alsoresults in rotation of the inner drive wheel component 1325. Forexample, the outer drive wheel component 1320 and the inner drive wheelcomponent 1325 can be inseparably coupled using an interference or pressfit assembly method such that friction between an inner circumferentialsurface of the outer drive wheel component 1320 and an outercircumferential surface of the inner drive wheel component 1325 retainsthe components of the drive wheel assembly 1250 in an assembledconfiguration. In other instances, the inner drive wheel component 1325and the outer drive wheel component 1320 can be assembled using anothersuitable method.

The inner drive wheel component 1325 can be a ring-shaped member with agenerally constant (i.e., having a constant inner diameter for greaterthan 75% of the length of the member) inner diameter sizing and agenerally variable outer diameter sizing (i.e., having a constant outerdiameter for less than 75% of the length of the member). In addition tobeing fixedly coupled with the outer drive wheel component 1320, theinner drive wheel component 1325 can be fixedly coupled with the innerring component of the bearing assembly 1315 and detachably coupled witha lock nut 1355 that is used to secure a hollow shaft 1350 to the rotorassembly 1200. For example, an inner circumferential surface of theinner drive wheel component 1325 can mate (e.g., using a friction fit)with an outer circumferential surface of the lock nut 1355, such thatrotation of the inner drive wheel component 1325 is transferred throughthe lock nut 1355 to cause rotation of the rotor assembly 1200. In otherinstances, another mechanical locking structure is used to causerotation of the rotor assembly 1200 is place of the lock nut 1355.

Still referring to FIG. 13, the sprue gate 920 can be inserted throughthe inner drive wheel component 1325 and the hollow shaft 1350 in orderto deposit molten copper in a region 1360 between an outer die component1340 and an inner die component 1345 of the rotor assembly 1200. Innerdie 1345 can be retained in its casting position by the hollow shaft1350, while outer die component 1340 can be retained in its castingposition by the spindle component 1305. In some examples presentedherein, the sprue gate 920 can be inserted through a gate hole 963disposed in the top wall 960 of the anti-oxidation shield 925. Spruegate 920 can include a funnel portion 1330 and a neck portion 1335. Forexample, funnel portion 1330 can have a frustoconical shape with atriangular cross-section. In other embodiments, funnel portion 1330 canhave any geometry required to introduce molten copper into the diecomponents 1340, 1345 at a desired flow rate. For example, funnelportion 1330 can have a semispherical shape with a semicircularcross-section. In some example instances, the funnel portion 1330 caninclude a filter or filtration media, such that the molten copper passesthrough the filter and filtration media to reduce the amount ofnon-metallic particles in the molten copper.

The neck portion 1335 can extend from the funnel portion 1330 such thatfunnel portion 1330 and neck portion 1335 share an uninterrupted wall.The length and diameter of the neck portion 1335 can depend on thedimensions of the rotor assembly 1200. For example, the outer diameterof the neck portion 1335 may range from 10 mm to 50 mm, while the lengthof the neck portion 1335 may range from 150 mm to 600 mm. The sprue gate920 can be retained in its casting position by thermally resistive tongsor any other suitable mechanical structure.

FIGS. 14 and 15, among others, respectively depict exploded isometricand isometric views of the rotor assembly 1200. Rotor assembly 1200 canbe installed within the centrifugal casting apparatus 900 during acentrifugal casting process. Rotor assembly 100 or rotor assembly 500,described above with reference to FIGS. 1-8, can be the result at thecompletion of the centrifugal casting process. Rotor assembly 1200 caninclude the rotor lamination stack 115, the first intermediary end ring120, the second intermediary end ring 125. Copper bars 130 can beinserted through the rotor slots located in the rotor lamination stack115, the first intermediary end ring 120, and the second intermediaryend ring 125 prior to the casting process.

The rotor assembly 1200 can further include a hollow shaft 1350 and alock nut 1355. The hollow shaft 1350 can include a shaft portion 1356and a flange portion 1353. The shaft portion 1356 can be insertedthrough the central bore 109 of the rotor lamination stack 115. In someexample instances, the shaft portion 1356 has an outer diameter rangingfrom 50 mm to 150 mm and an inner diameter ranging from 20 mm to 120 mm.The inner diameter of the shaft portion 1356 can be sized to permit thesprue gate 920 to pass easily through the shaft portion 1356. Forexample, a clearance region ranging from 2 mm to 10 mm can be maintainedbetween the sprue gate 920 and the shaft portion 1356

The hollow shaft 1350 can be secured by threadably coupling the lock nut1355 to the shaft portion 1356. For example, the lock nut 1355 can be aflange nut that is secured flush against an exterior surface of thesecond intermediary end ring 125. In other example instances, the locknut 1355 can be any suitable type of nut, including, but not limited to,a hex nut, a wing nut, a square nut, or a cap nut. In still furtherinstances, a washer, spacer, or other hardware can be arranged betweenthe second intermediary end ring 125 and the lock nut 1355.

The flange portion 1353 can have a hexagonal shape and can be arrangedbetween the first intermediary end ring 120 and the inner die component1345. In an example instance, the flange portion 1353 can be installedflush against the intermediary end ring 120, while a clearance regionranging from 1 mm to 10 mm is maintained between the flange portion 1353and the inner die component 1345. In other example instances, the flangeportion 1353 can be installed flush against the inner die component 1345while a clearance region is maintained between the flange portion 1353and the intermediary end ring 120.

The rotor assembly 1200 can further include an inner die component 1345and an outer die component 1340. The inner die component 1345 can bespaced apart from the outer die component 1340. During the centrifugalcasting process, molten copper can be directed to a region (i.e., region1360, depicted in FIG. 13) between the inner die component 1345 and theouter die component 1340. The shape of the casted end rings (e.g., endrings 105, 110, 505, 510) can be determined by the geometry of theregion between the inner die component 1345 and the outer die component1340. In some example instances, the inner die component 1345 can beretained on inner circumferential surfaces of the copper bars 130 usinga friction fit. The outer die component 1340 can be retained on outercircumferential surfaces of the rotor lamination stack 115 using afriction fit.

FIG. 16, among others, depicts a top elevation view of the rotorlamination stack 115. Each lamination disc can include bore 109 stampedor otherwise formed at the center of each disc. In some exampleinstances, the bore 109 can have a substantially circular cross-sectionwith notch features 1605. A “substantially circular cross-section” canrefer to a cross-section in which at least 75% of the perimeter of thebore 109 conforms to a circular geometry. In other example instances,the bore 109 can have any other suitable geometry, including, but notlimited to, a square, rectangular, or triangular cross-section. Notchfeatures 1605 can be utilized in the alignment of each lamination discrelative to each other, and in the alignment of a shaft passing throughthe bore 109. For example, the shaft can include recess features thatreceive the notch features 1605 to prevent rotation of the shaftrelative to the rotor lamination stack 115. Although FIG. 16 depicts thebore 109 as having two rectangular notch features 1605 spaced 180°apart, any number of notch features with any geometry and orientationcan be utilized.

Each lamination disc of the rotor lamination stack 115 can furtherinclude multiple rotor slots 1610 distributed evenly about thecircumference of each disc. For example, each lamination disc caninclude a number of slots ranging from 32 to 100 slots. FIG. 17, amongothers, depicts a detail view of a rotor slot 1610 of the rotorlamination stack 115. Each rotor slot 1610 can have a tapered shape witha first end that is narrower than a second end. The first end of slot1610 can be located closer to the central bore 109 than the second end.In some example instances, the height 1705 of the slot 1610 can rangefrom 18 mm to 22 mm, the first end width 1710 of the slot 1610 can rangefrom 1.0 mm to 2.5 mm, and the second end width 1715 of the slot 1610can range from 2 mm to 5 mm. In other example instances, the dimensionsof the rotor slot 1610 can be larger or smaller to accommodate copperbars (i.e., copper bars 130) having correspondingly larger or smallerdimensions.

FIG. 18, among others, depicts a side cross-sectional view of the rotorlamination stack 115. In some example instances, the outer diameter 1805of the rotor lamination stack 115 (i.e., the outer diameter of eachindividual lamination disc) can range from 132 mm to 155 mm. The height1810 of the rotor lamination stack 115 can range from 100 mm to 155 mm.The diameter 1815 of the central bore 109 can range from 40 mm to 50 mm.In other example instances, any or all of the outer diameter 1805, theheight 1810, and the diameter 1815 can be larger or smaller depending onthe specifications of the induction motor in which the rotor laminationstack 115 is installed.

FIGS. 19 and 20, among others, depict isometric views of example innerdie components 1345 and 2000. Either inner die component 1345 or 2000can be nested inside an outer die component in the rotor assembly 1200during the centrifugal casting process (e.g., as shown in FIG. 14). Invarious example embodiments, the inner die components 1345, 2000 can befabricated from a high temperature-resistant ceramic material or a metal(e.g., stainless steel). Specifically referring to FIG. 19, an inner diecomponent 1345 is depicted. Inner die component 1345 can include a baseplate 1905, an outer circumferential wall 1910, and an innercircumferential wall 1915. In some example presented herein, the baseplate 1905 can have a ring shape. For example, the base plate 1905 canhave an outer diameter (i.e., the diameter at the intersection betweenthe base plate 1905 and the outer circumferential wall 1910) rangingfrom 100 mm to 300 mm, and an inner diameter (i.e., the diameter at theintersection between the base plate 1905 and the inner circumferentialwall 1915) ranging from 15 mm to 60 mm.

The outer circumferential wall 1910 can extend vertically from the baseplate 1905 and can have a ring-shaped structure. For example, the outercircumferential wall 1910 can have a height above the base plate 1905ranging from 10 mm to 60 mm. In some examples presented herein, theouter circumferential wall 1910 is substantially perpendicular (i.e.,±10°) to the base plate 1905. In other examples presented herein, theouter circumferential wall 1910 can be situated at a draft angle of 15°or more relative to the base plate 1905. Inner circumferential wall 1915can extend vertically from the base plate 1905 and can have aring-shaped structure that surrounds a central bore 1920. For example,the inner circumferential wall 1915 can have a height above the baseplate 1905 ranging from 10 mm to 60 mm. In some examples presentedherein, the inner circumferential wall 1915 is substantiallyperpendicular (i.e., ±10°) to the base plate 1905. In other examplespresented herein, the inner circumferential wall 1915 can be situated ata draft angle of 15° or more relative to the base plate 1905.

Referring now to FIG. 20, an inner die component 2000 is depicted. Theinner die component 2000 can be used in the place of inner die component1345 when the casted rotor assembly requires the additional coolingafforded by cooling fins. For example, the inner die component 2000 canbe used to fabricate the first end ring 505 and the second end ring 510containing cooling fins described and depicted above with reference toFIGS. 5-8. The inner die component 2000 can include a base plate 2005,an outer circumferential wall 2010, and an inner circumferential wall2015. In some examples presented herein, the base plate 2005 can have aring shape with a convoluted (i.e., back and forth) outer perimetergeometry. For example, the base plate 2005 can have a minimum outerdiameter (i.e., the innermost point at which the base plate 2005intersects the outer circumferential wall 2010) ranging from, 100 mm to200 mm, and a maximum outer diameter (i.e., the outermost point at whichthe base plate 2005 intersects the outer circumferential wall 2010)ranging from 200 mm to 300 mm. The base plate 2005 can further have aninner diameter (i.e., the diameter at the intersection between the baseplate 2005 and the inner circumferential wall 2015) ranging from 10 mmto 60 mm.

The outer circumferential wall 2010 can extend vertically from the baseplate 2005 and can have a convoluted ring-shaped structure. The geometryof the convolutions (e.g., depth, width) can include any dimensionsrequired to produce a desired surface area and number of casted coolingfins. The outer circumferential wall 2010 can have a height above thebase plate 2005 ranging from 15 mm to 50 mm. In some examples presentedherein, the outer circumferential wall 2010 is substantiallyperpendicular (i.e., ±10°) to the base plate 2005. In other examplespresented herein, the outer circumferential wall 2010 can be situated ata draft angle of 15° or more relative to the base plate 2005. The innercircumferential wall 2015 can extend vertically from the base plate 2005and can have a ring-shaped structure that surrounds a central bore 2020.In some example instances, the geometric characteristics of the innercircumferential wall 2015 (i.e., height, angle relative to the baseplate 2005) are identical or substantially similar (i.e., ±10%) to thegeometric characteristics of the inner circumferential wall 1915described above with respect to FIG. 19.

FIGS. 21 and 22, among others, depict isometric views of example outerdie components 1340 and 2200. Either outer die component 1340 or 2200can be nested outside an inner die component in the rotor assembly 1200during the centrifugal casting process (e.g., as shown in FIG. 14). Invarious example embodiments, the outer die components 1340, 2200 can befabricated from a high temperature-resistant ceramic material or a metal(e.g., stainless steel). Specifically referring to FIG. 21, an outer diecomponent 1340 is depicted. The outer die component 1340 can include abase plate 2105, an outer circumferential wall 2110, and a centralprojection 2120. In some examples presented herein, the base plate 2105can have a circular shape. For example, base plate 2105 can have anouter diameter (i.e., the diameter at the intersection between the baseplate 2105 and the outer circumferential wall 2110) ranging from 100 mmto 300 mm. In other examples presented herein, base plate 2105 can havea square shape, a rectangular shape, or any other desired shape. Theouter circumferential wall 2110 can extend vertically from the baseplate 2105. For example, the outer circumferential wall 2110 can have aheight ranging from 10 mm to 60 mm above the base plate 2105. In someexamples presented herein, the outer circumferential wall 2110 issubstantially perpendicular (i.e., ±10°) to the base plate 2105. Inother examples presented herein, the outer circumferential wall 2110 canbe situated at a draft angle of 15° or more relative to the base plate2105.

The outer circumferential wall 2110 can include multiple outgassingports 2115 distributed about the perimeter of the outer circumferentialwall 2110. The outgassing ports 2115 can be formed as flareddiscontinuities in the outer circumferential wall 2110. For example, theouter circumferential wall 2110 can be cylindrical (i.e., having acircular cross-section) except in the region of the outgassing ports2115. The outgassing ports 2115 can be used to determine when thecentrifugal casting process is completed. For example, a technician canstop pouring molten copper through the sprue gate 920 as soon as thecopper has flowed to the outer circumferential wall 2110 and is visiblefrom the outgassing ports 2115. In some example instances, the outer diecomponent 1340 can include four outgassing ports 2115 distributed at 90°intervals about the outer circumferential wall 2110. In other instances,the outer die component 1340 can include any number of outgassing ports2115, having any geometry about the outer circumferential wall 2110.

The central projection 2120 can form a continuous surface with the baseplate 2105. For example, the central projection 2120 can be cone-shapedwith a height above the base plate 2105 ranging from 10 mm to 60 mm. Thegeometry of the central projection 2120 can permit the outer diecomponent 1340 to mate with the spindle component 1305 of the base plateassembly 1205 when the rotor assembly 1200 is mounted in the spinnerassembly 905. In other example instances, the central projection 2120can be any other shape required to permit the outer die component 1340to mate with the spindle component 1305 of the base plate assembly 1205.

Turning now to FIG. 22, an outer die component 2200 is depicted. Theouter die component 2200 can include a base plate 2205, an outercircumferential wall 2210, and a central projection 2220. In someexamples presented herein, the base plate 2205 can have a circularshape. For example, base plate 2205 can have an outer diameter (i.e.,the diameter at the intersection between the base plate 2205 and theouter circumferential wall 2210) ranging from 100 mm to 300 mm. In otherexamples presented herein, base plate 2205 can have a square shape, arectangular shape, or any other desired shape. The outer circumferentialwall 2210 can extend vertically from the base plate 2205. For example,the outer circumferential wall 2210 can have a height ranging from 10 mmto 60 mm above the base plate 2205. In some examples presented herein,the outer circumferential wall 2210 is substantially perpendicular(i.e., ±10°) to the base plate 2205. In other examples presented herein,the outer circumferential wall 2210 can be situated at a draft angle of15° or more relative to the base plate 2205.

The outer circumferential wall 2210 can include multiple retention slots2215. The retention slots 2215 can be utilized to permit the escape ofair and gas during the casting process. In some examples presentedherein, the width of each slot 2215 can range from 2 mm to 3 mm, and theheight of each slot 2215 can range from 1 mm to 2 mm. Although FIG. 22depicts the outer die component 2200 as having six retention slots 2215evenly distributed about the outer circumferential wall 2210, in otherexample instances, the outer die component 2200 can include any numberof retention slots 2215, situated in any orientation on the outercircumferential wall 2210. The outer die component 2200 is further shownto include a central projection 2220. In some example instances, thegeometric characteristics of the central projection 2220 (i.e., height)are identical or substantially similar (i.e., ±10%) to the geometriccharacteristics of the central projection 2120 described above withrespect to FIG. 21.

Referring now to FIG. 23, a cross-sectional view of an electric vehicle2300 installed with an induction motor 2305 is depicted. The inductionmotor 2305 can include a centrifugally cast rotor assembly as describedand depicted above according to any of the FIGS. 1-22. The electricvehicle 2300 can include a chassis 2310 (e.g., a frame, internal frame,or support structure). The chassis 2310 can support various componentsof the electric vehicle 2300. The chassis 2310 can span a front portion2315 (e.g., a hood or bonnet portion), a body portion 2320, and a rearportion 2325 (e.g., a trunk portion) of the electric vehicle 2300. Theinduction motor 2305 can be installed or placed within the electricvehicle 2300. The induction motor 2305 can be installed on the chassis2310 of the electric vehicle 2300 within the front portion 2315, thebody portion 2320, or the rear portion 2325.

FIG. 24 depicts a flow diagram of a method 2400 of initiating acentrifugal casting process for a rotor core assembly 1200 of aninduction motor. The method 2400 can be performed or implemented usingthe components detailed above in conjunction with FIGS. 1-23. The method2400 can include stacking multiple lamination discs (ACT 2405). Forexample, the multiple lamination discs can be stacked and compressedusing a press machine to form a rotor core assembly 115. The laminationdiscs of the rotor core assembly 115 can be coated with an oxide inorder to electrically insulate the metal discs from each other.Electrically insulating spacer discs can also be placed between adjacentmetal discs.

The method 2400 can include installing intermediary end ring components(ACT 2410). For example, the end ring components can be installed atboth ends of the rotor core assembly 1200. A technician can manuallydispose a first intermediary end ring 120 such that an interior surfaceof the first intermediary end ring 120 contacts the first end surface112 proximate the first end 101 of the rotor lamination stack 115.Similarly, a technician can manually dispose a second intermediary endring 125 such that an interior surface of the second intermediary endring 125 contacts the second end surface 118 proximate the second end103 of the rotor lamination stack 115.

The method 2400 can include inserting a hollow shaft 1350 into the rotorcore assembly 1200 and securing a nut (ACT 2415). For example, the nutcan be lock nut 1355. The centrifugal casting process can commence bycasting the end ring at the first end 101 (i.e., proximate the firstintermediary end ring 120). Therefore, the shaft portion 1356 of thehollow shaft 1350 can be first inserted through the first intermediaryend ring 120, next through the rotor lamination stack 115, and finallythrough the second intermediary end ring 125. In some examples presentedherein, the lock nut 1355 can be secured by a technician by fingertightening the lock nut 1355 flush against an exterior surface of thesecond intermediary ring 125. In other examples presented herein, thelock nut 1355 can be secured flush against the exterior surface of thesecond intermediary ring using a tool (e.g., an adjustable wrench, acombination wrench, an open-end wrench, a ratchet wrench, a torquewrench). For example, a torque wrench can be used to tighten the locknut 1355 to specified torque ranging from 100 N-m to 800 N-m.

The method 2400 can include positioning an inner die component 1345 andan outer die component 1340 (ACT 2420). The inner die component 1345 andthe outer die component 1340 can be installed at the first end 101 ofthe rotor core assembly 1200. For example, a technician can locate theinner die component 1345 such that the inner circumferential wall 1915is retained within an interior surface of the shaft portion 1356 of thehollow shaft 1350 using a friction fit. The technician can subsequentlylocate the outer die component 1340 such that the outer circumferentialwall 2110 is retained on outer circumferential surfaces of the rotorlamination stack 115 using a friction fit. In some embodiments, a moldcoating can be sprayed between the inner die component 1345 and theouter die component 1340. The mold coating can aid acceleration ofmolten metal, produce a specific surface finish, and enable easyextraction of the cast end ring from the die components 1340 and 1345.

The method 2400 can include inserting copper bars 130 (ACT 2425). Thecopper bars 130 can be inserted into rotor slots of the rotor coreassembly 1200. For example, a technician can insert each copper bar 130through the intermediary end rings 120, 125 and the rotor laminationstack 115 until each rotor slot 1610 is populated by a copper bar 130. Amachine with tooling designed for gripping and inserting the copper bars130 can also be utilized.

The method 2400 can include pre-heating the rotor assembly 1200 (ACT2430). For example, the pre-heating step can be accomplished by placingthe rotor assembly 1200 into a kiln (not shown). In some examplespresented herein, the pre-heating step can include heating the rotorassembly 1200 to a temperature ranging from 600° C. to 800° C. Duringthe pre-heating step, the copper bars 130 can expand to fill the rotorslots 1610. Once the copper bars 130 have expanded into the rotor slots1610, the copper bars 130 can be fixedly coupled with the rotorlamination stack 115 and the intermediary end rings 120, 125.

The method 2400 can include mounting the rotor core assembly 1200 (ACT2435). For example, the rotor core assembly 1200 can be mounted to aspinner assembly 905. Mounting the rotor core assembly 1200 can includea technician removing the upper plate assembly 1230 from the spinnerassembly 905 (i.e., removing the fasteners securing the first armportion 1240 to the first upper portion 1220 and the second arm portion1245 to the second upper portion 1225). The technician can next placethe rotor core assembly 1200 atop the base plate assembly 1205 such thatthe spindle component 1305 mates with the central projection 2120 of theouter die component 1340, and the rotor core assembly 1200 can rotatefreely with the spindle component 1305. The mounting process canconclude with the technician replacing the upper plate assembly 1230 onthe spinner assembly 905 (i.e., replacing the fasteners securing thefirst arm portion 1240 to the first upper portion 1220 and the secondarm portion 1245 to the second upper portion 1225).

The method 2400 can include heating copper casting material (ACT 2440).For example, a technician can place pellets of copper casting materialinto a furnace crucible (not shown). The copper casting material can beoxygen-free electrolytic copper, which can be referred to as OFE orC10100 copper. OFE copper has the highest purity for standardized copperand has a purity grade of 99.99%. In some examples presented herein, thecopper casting material can be heated to a temperature ranging from1100° C. to 1200° C.

The method 2400 can include installing an anti-oxidation shield 925 (ACT2445). For example, the anti-oxidation shield 925 can be installed overthe casting apparatus 900. Installing the anti-oxidation shield 925 caninclude positioning the main body portion 930 over the spinner assembly905, the motor assembly 910, and the rotor assembly 1200.

The method 2400 can include inserting a sprue gate 920 (ACT 2450). Thesprue gate 920 can be inserted into the rotor core assembly 1200. Forexample, a technician can insert the neck portion 1335 of the sprue gate920 through the shaft portion 1356 of the hollow shaft 1350. In someinstances, the sprue gate 920 can be retained with the rotor coreassembly 1200 using thermally resistive tongs or any other suitablemechanical structure.

The method 2400 can include filling a space with anti-oxidation gas (ACT2455). In some instances, the anti-oxidation gas can fill the spaceencapsulated by the anti-oxidation shield 925. The anti-oxidation gascan be pure nitrogen, or a nitrogen-containing mixture. The gas can alsobe a pure gas or a mixture containing one of the following: argon,chlorine, Freon, or hexachloroethane.

FIG. 25 depicts a flow diagram of a method 2500 of centrifugally castinga rotor assembly 1200 of an induction motor in an electric vehicle. Themethod 2500 can be performed or implemented using the componentsdetailed above in conjunction with FIGS. 1-23. In some examplespresented herein, the method 2500 is performed immediately subsequentthe performance of the method 2400. The method 2500 can include spinningthe rotor core assembly 1200 (ACT 2505). For example, spinning the rotorcore assembly 1200 can include a technician operating the motor assembly910. Operating the motor assembly 910 can cause rotation of the drivewheel 965, which can transmit power to the drive belt 915. The drivebelt 915 can transmit a rotational force to the drive wheel assembly1250, which can be transmitted to the rotor core assembly 1200 throughthe coupling of the inner drive wheel component 1325 to the lock nut1355. In some examples presented herein, the drive speed provided by themotor assembly 910 is sufficient to rotate the rotor core assembly 1200at a speed ranging from 2500 revolutions per minute (RPM) to 3000 RPM.

The method 2500 can include pouring copper casting material (ACT 2510).For example, the copper casting material can be poured through the spruegate 920 and into the rotor core assembly 1200. The molten coppercasting material can be transferred from the furnace crucible to aladle, and a technician can use the ladle to pour the molten copperthrough the funnel portion 1330 and the neck portion 1335 of the spruegate 920. The neck portion 1335 deposits the molten copper through thecentral bore 109 and into the region 1360 between the inner diecomponent 1345 and the outer die component 1340. Performing thecentrifugal casting process at a lowest possible pouring temperature canreduce the size of the copper grains in the finished end rings. Afterthe copper casting material is poured into the region 1360 between theinner die component 1345 and the outer die component 1340,solidification takes place from the outer circumferential wall 2110 ofthe outer die component 1340, to the inner circumferential wall 1915 ofthe inner die component 1345.

The method 2500 can include cooling and removing the rotor core assembly1200 (ACT 2515). For example, the rotor core assembly 1200 can be cooledand removed from the spinner assembly 905. A technician can determinewhen to halt the spinning process and begin the cooling process based onthe visibility of copper in the region of the outgassing ports 2115 ofthe outer die component 1340. For example, the spinning process can behalted and the cooling process can begin after the rotor core assembly1200 has been spinning for a period ranging from 30 seconds to fiveminutes. In an example instance, the spinning period can be one minute.The cooling period for the rotor core assembly 1200 can range from 180minutes to 600 minutes. The rotor core assembly 1200 can be air cooledto room temperature without the use of coolants or refrigerantequipment, as artificial acceleration of the cooling process can reducethe quality of the casted end ring. Removing the rotor core assembly1200 from the spinner assembly can include a technician removing theupper plate assembly 1230 from the spinner assembly 905 (i.e., removingthe fasteners securing the first arm portion 1240 to the first upperportion 1220 and the second arm portion 1245 to the second upper portion1225). Once the upper plate assembly 1230 has been removed from thespinner assembly 905, the outer die component 1340 can be unmated fromthe spindle component 1305 and the rotor core assembly 1200 can beremoved from the spinner assembly 905.

The method 2500 can include releasing the nut and removing the shaft1350 from the rotor core assembly 1200 (ACT 2520). For example, the nutcan be lock nut 1355. A technician can release the lock nut 1355 by handor through the use of an appropriate tool. Prior to removing the hollowshaft 1350 from the rotor core assembly 1200, the technician can removethe outer die component 1340 and the inner die component 1345 to revealthe first centrifugally cast copper end ring 105. In some examplespresented herein, a technician can also perform various inspection stepsto ensure the quality of the first centrifugally cast end ring 105. Forexample, the technician can inspect qualities including, but not limitedto, the porosity and grain size of the first centrifugally cast end ring105.

The method 2500 can include flipping the rotor core assembly 1200 andreplacing the shaft 1350 and the nut (ACT 2525). For example, the nutcan be lock nut 1355. By flipping the rotor core assembly 1200, theshaft portion 1356 of the hollow shaft 1350 can be first insertedthrough the second intermediary end ring 125, next through the rotorlamination stack 115, and finally through the first intermediary endring 120. In some examples presented herein, the lock nut 1355 can besecured by a technician by finger tightening the lock nut 1355 flushagainst an exterior surface of the first intermediary ring 120. In otherexamples presented herein, the lock nut 1355 can be secured flushagainst the exterior surface of the first intermediary ring 120 using atool (e.g., an adjustable wrench, a combination wrench, an open-endwrench, a ratchet wrench, a torque wrench). For example, a torque wrenchcan be used to tighten the lock nut 1355 to specified torque rangingfrom 100 N-m to 800 N-m.

The method 2500 can include positioning the inner die component 1345 andthe outer die component 1340 (ACT 2530). For example, the inner diecomponent 1345 and the outer die component 1340 can be installed at thesecond end 103 of the rotor core assembly 1200. A technician can locatethe inner die component 1345 such that the inner circumferential wall1915 is retained within an interior surface of the shaft portion 1356 ofthe hollow shaft 1350 using a friction fit. The technician cansubsequently locate the outer die component 1340 such that the outercircumferential wall 2110 is retained on outer circumferential surfacesof the rotor lamination stack 115 using a friction fit. In someembodiments, a mold coating can be sprayed between the inner diecomponent 1345 and the outer die component 1340. The mold coating canaid acceleration of molten metal, produce a specific surface finish, andenable easy extraction of the cast end ring from the die components 1340and 1345.

The method 2500 can include repeating the centrifugal casting process(ACT 2535). For example, the centrifugal casting process can be repeatedfor the second end 103 of the rotor core assembly 1200. Repeating thecentrifugal casting process for the second end of the rotor coreassembly can include repeating the performance of ACTS 2435-2450 ofmethod 2400 and the performance of ACTS 2505-2520 of method 2500 to formthe second centrifugally cast end ring 110. In some examples presentedherein, every step inclusive of ACTS 2435-2450 and 2505-2520 areperformed for the second end 103 of the rotor core assembly 1200. Inother examples, one or more steps can be omitted.

Method 2500 can conclude by performing a surface finishing process onthe first centrifugally cast end ring 105 and the second centrifugallycast end ring 110. For example, the surface finishing process couldinclude one or more of the following processes: abrasive blasting,sandblasting, burnishing, electropolishing, grinding, vibratoryfinishing, polishing, buffing, and shot peening. In some examplespresented herein, the method 2500 can conclude with a technicianperforming various inspection steps to ensure the quality of the firstcentrifugally cast end ring 105 and the second centrifugally cast endring 110. For example, the technician can inspect the porosity, grainsize, structural strength, and finished dimensions of the end rings 105,110. The centrifugal casting process generally results in gooddimensional size control, and dimensional tolerances of ±1 mm can beachieved, meaning that the centrifugal casting processes describedherein can be utilized in the mass production of centrifugally castedrotor assemblies.

FIG. 26 depicts a method 2600 for providing an induction motor for anelectric vehicle. The functionalities of the method 2600 can beimplemented using the systems or apparatuses discussed above inconjunction with FIGS. 1-25. The method 2600 can include providing aninduction motor 2305 (ACT 2605). The induction motor 2305 can beinstalled in an electric vehicle 2300. The induction motor 2305 caninclude a motor shaft, a stator assembly, and a rotor assembly 100. Therotor assembly 100 can include a rotor lamination stack 115 having acylindrical shape that defines a central axis 106. The rotor laminationstack 115 can terminate in a first end surface 112 and a second endsurface 118. The rotor assembly 100 can also include a central axialbore 109 that extends from the first end surface 112 of the rotorlamination stack 115 to the second end surface 118 of the rotorlamination stack 115. The rotor lamination stack 115 can includemultiple lamination discs. Each of the lamination discs can includemultiple rotor slots 1610. Multiple copper bars 130 can be disposedwithin the rotor slots 1610. Each copper bar 130 extends beyond thefirst end surface 112 and the second end surface 118. The rotor assembly100 can also include a first intermediary ring 120 disposed at the firstend surface 112, and a second intermediary ring 125 disposed at thesecond end surface 118. The rotor assembly can also include acentrifugally cast first copper end ring 105 that electrically andmechanically couples each of the copper bars 130 proximate the first endsurface 112, and a centrifugally cast second copper end ring 110 thatelectrically and mechanically couples each of the copper bars 130proximate the second end surface 118. Each of the centrifugally castfirst copper end ring 105 and the centrifugally cast second copper endring 110 can be formed using a centrifugal casting process after thecopper bars 130 are inserted into the rotor slots 1610.

FIG. 27 depicts a method 2700 for providing a centrifugally cast copperrotor assembly of an induction motor in an electric vehicle. Thefunctionalities of the method 2700 can be implemented using the systemsor apparatuses discussed above in conjunction with FIGS. 1-25. Themethod 2700 can include providing a centrifugally cast copper rotorassembly 100 (ACT 2705). The rotor assembly 100 can include a rotorlamination stack 115 having a cylindrical shape that defines a centralaxis 106. The rotor lamination stack 115 can terminate in a first endsurface 112 and a second end surface 118. The rotor assembly 100 canalso include a central axial bore 109 that extends from the first endsurface 112 of the rotor lamination stack 115 to the second end surface118 of the rotor lamination stack 115. The rotor lamination stack 115can include multiple lamination discs. Each of the lamination discs caninclude multiple rotor slots 1610. Multiple copper bars 130 can bedisposed within the rotor slots 1610. Each copper bar 130 extends beyondthe first end surface 112 and the second end surface 118. The rotorassembly 100 can also include a first intermediary ring 120 disposed atthe first end surface 112, and a second intermediary ring 125 disposedat the second end surface 118. The rotor assembly can also include acentrifugally cast first copper end ring 105 that electrically andmechanically couples each of the copper bars 130 proximate the first endsurface 112, and a centrifugally cast second copper end ring 110 thatelectrically and mechanically couples each of the copper bars 130proximate the second end surface 118. Each of the centrifugally castfirst copper end ring 105 and the centrifugally cast second copper endring 110 can be formed using a centrifugal casting process after thecopper bars 130 are inserted into the rotor slots 1610.

FIG. 28 depicts a method 2800 for providing an apparatus tocentrifugally cast a copper rotor assembly of an induction motor in anelectric vehicle. The functionalities of the method 2800 can beimplemented using the systems or apparatuses discussed above inconjunction with FIGS. 1-25. The method 2800 can include providing anapparatus 900 to centrifugally cast a copper rotor assembly (ACT 2805).The method can include providing a rotor assembly 1200 with acylindrical shape that defines a central axis 106. The rotor assemblycan terminate in a first end 101 and a second end 103. The method caninclude providing an inner die component 1345, and providing an outerdie component 1340. Each of the inner die component 1345 and the outerdie component 1340 can be disposed at the first end 101 of the rotorassembly. The method can include providing a spinner assembly 905. Thespinner assembly 905 can include a lower structure 1205, an upperstructure 1230, and a sidewall structure 1210. The lower structure 1205can be disposed beneath the rotor assembly 1200 and can include a baseplate 1300, a spindle component 1305 configured to mate with the outerdie component 1340, and a first bearing assembly 1310. The first bearingassembly 1310 can include a first inner ring component 1313 and a firstouter ring component 1316. The first outer ring component 1316 can befixedly coupled with the base plate 1300 and the first inner ringcomponent 1313 can be fixedly coupled with the spindle component 1305such that the spindle component 1305 is permitted to rotate with therotor assembly 1200 about the central axis 106 relative to the baseplate 1300. The upper structure 1230 can be disposed above the rotorassembly 1200 and can include an upper plate 1235, a drive wheelcomponent 1325 configured to mate with the rotor assembly 1200, and asecond bearing assembly 1315. The second bearing assembly 1315 caninclude a second inner ring component 1318 and a second outer ringcomponent 1321. The second outer ring component 1321 can be fixedlycoupled with the upper plate 1235 and the second inner ring component1318 can be fixedly coupled with the drive wheel component 1325 suchthat the drive wheel component 1325 is permitted to rotate with therotor assembly 1200 about the central axis 106 relative to the upperplate 1235. The sidewall structure 1210 can couple the lower structure1205 to the upper structure 1230. The method can further includeproviding a motor 910 that drive rotation of the drive wheel component1325.

FIG. 29 depicts a method 2900 for providing a spinner assembly 905 foruse in the centrifugal casting process of a copper rotor assembly of aninduction motor in an electric vehicle (ACT 2905). The functionalitiesof the method 2900 can be implemented using the systems or apparatusesdiscussed above in conjunction with FIGS. 1-25. The spinner assembly 905can include a lower structure 1205, an upper structure 1230, and asidewall structure 1210. The lower structure 1205 can be disposedbeneath the rotor assembly 1200 and can include a base plate 1300, aspindle component 1305 configured to mate with the outer die component1340, and a first bearing assembly 1310. The first bearing assembly 1310can include a first inner ring component 1313 and a first outer ringcomponent 1316. The first outer ring component 1316 can be fixedlycoupled with the base plate 1300 and the first inner ring component 1313can be fixedly coupled with the spindle component 1305 such that thespindle component 1305 is permitted to rotate with the rotor assembly1200 about the central axis 106 relative to the base plate 1300. Theupper structure 1230 can be disposed above the rotor assembly 1200 andcan include an upper plate 1235, a drive wheel component 1325 configuredto mate with the rotor assembly 1200, and a second bearing assembly1315. The second bearing assembly 1315 can include a second inner ringcomponent 1318 and a second outer ring component 1321. The second outerring component 1321 can be fixedly coupled with the upper plate 1235 andthe second inner ring component 1318 can be fixedly coupled with thedrive wheel component 1325 such that the drive wheel component 1325 ispermitted to rotate with the rotor assembly 1200 about the central axis106 relative to the upper plate 1235. The sidewall structure 1210 cancouple the lower structure 1205 to the upper structure 1230.

While operations are depicted in the drawings in a particular order,such operations are not required to be performed in the particular ordershown or in sequential order, and all illustrated operations are notrequired to be performed. Actions described herein can be performed in adifferent order.

Having now described some illustrative implementations, it is apparentthat the foregoing is illustrative and not limiting, having beenpresented by way of example. In particular, although many of theexamples presented herein involve specific combinations of method actsor system elements, those acts and those elements can be combined inother ways to accomplish the same objectives. Acts, elements andfeatures discussed in connection with one implementation are notintended to be excluded from a similar role in other implementations orimplementations.

The phraseology and terminology used herein is for the purpose ofdescription and should not be regarded as limiting. The use of“including” “comprising” “having” “containing” “involving”“characterized by” “characterized in that” and variations thereofherein, is meant to encompass the items listed thereafter, equivalentsthereof, and additional items, as well as alternate implementationsconsisting of the items listed thereafter exclusively. In oneimplementation, the systems and methods described herein consist of one,each combination of more than one, or all of the described elements,acts, or components.

Any references to implementations or elements or acts of the systems andmethods herein referred to in the singular can also embraceimplementations including a plurality of these elements, and anyreferences in plural to any implementation or element or act herein canalso embrace implementations including only a single element. Referencesin the singular or plural form are not intended to limit the presentlydisclosed systems or methods, their components, acts, or elements tosingle or plural configurations. References to any act or element beingbased on any information, act or element can include implementationswhere the act or element is based at least in part on any information,act, or element.

Any implementation disclosed herein can be combined with any otherimplementation or embodiment, and references to “an implementation,”“some implementations,” “one implementation” or the like are notnecessarily mutually exclusive and are intended to indicate that aparticular feature, structure, or characteristic described in connectionwith the implementation can be included in at least one implementationor embodiment. Such terms as used herein are not necessarily allreferring to the same implementation. Any implementation can be combinedwith any other implementation, inclusively or exclusively, in any mannerconsistent with the aspects and implementations disclosed herein.

References to “or” can be construed as inclusive so that any termsdescribed using “or” can indicate any of a single, more than one, andall of the described terms. For example, a reference to “at least one of‘A’ and ‘B’” can include only ‘A’, only ‘B’, as well as both ‘A’ and‘B’. Such references used in conjunction with “comprising” or other openterminology can include additional items.

Where technical features in the drawings, detailed description or anyclaim are followed by reference signs, the reference signs have beenincluded to increase the intelligibility of the drawings, detaileddescription, and claims. Accordingly, neither the reference signs northeir absence have any limiting effect on the scope of any claimelements.

Modifications of described elements and acts such as variations insizes, dimensions, structures, shapes and proportions of the variouselements, values of parameters, mounting arrangements, use of materials,colors, orientations can occur without materially departing from theteachings and advantages of the subject matter disclosed herein. Forexample, elements shown as integrally formed can be constructed ofmultiple parts or elements, the position of elements can be reversed orotherwise varied, and the nature or number of discrete elements orpositions can be altered or varied. Other substitutions, modifications,changes and omissions can also be made in the design, operatingconditions and arrangement of the disclosed elements and operationswithout departing from the scope of the present disclosure.

The systems and methods described herein can be embodied in otherspecific forms without departing from the characteristics thereof. Scopeof the systems and methods described herein is thus indicated by theappended claims, rather than the foregoing description, and changes thatcome within the meaning and range of equivalency of the claims areembraced therein.

Systems and methods described herein may be embodied in other specificforms without departing from the characteristics thereof. For example,descriptions of positive and negative electrical characteristics may bereversed. For example, elements described as negative elements caninstead be configured as positive elements and elements described aspositive elements can instead by configured as negative elements.Further relative parallel, perpendicular, vertical or other positioningor orientation descriptions include variations within +/−10% or +/−10degrees of pure vertical, parallel or perpendicular positioning.References to “approximately,” “about” “substantially” or other terms ofdegree include variations of +/−10% from the given measurement, unit, orrange unless explicitly indicated otherwise. Coupled elements can beelectrically, mechanically, or physically coupled with one anotherdirectly or with intervening elements. Scope of the systems and methodsdescribed herein is thus indicated by the appended claims, rather thanthe foregoing description, and changes that come within the meaning andrange of equivalency of the claims are embraced therein.

What is claimed is:
 1. A rotor assembly for an induction motor of anelectric vehicle, comprising: a rotor lamination stack having acylindrical shape that defines a central axis, the rotor laminationstack terminates in a first end surface and a second end surface, acentral axial bore extends from the first end surface of the rotorlamination stack to the second end surface of the rotor laminationstack; the rotor lamination stack has a plurality of lamination discs,each of the plurality of lamination discs having a plurality of rotorslots; a plurality of copper bars disposed within the plurality of rotorslots, each of the plurality of copper bars extends beyond the first endsurface of the rotor lamination stack and beyond the second end surfaceof the rotor lamination stack; a first intermediary end ring disposed atthe first end surface of the rotor lamination stack, the firstintermediary end ring having multiple rotor slots; a second intermediaryend ring disposed at the second end surface of the rotor laminationstack, the second intermediary end ring having multiple rotor slots; acentrifugally cast first copper end ring that electrically andmechanically couples each of the plurality of copper bars proximate thefirst end surface of the rotor lamination stack; an interior face of thecentrifugally cast first copper end ring having a plurality of recessesto couple with the plurality of copper bars; an exterior face of thecentrifugally cast first copper end ring having an entirely solidsurface; an exterior surface of the first intermediary end ring directlycontacts the interior face of the centrifugally cast first copper endring; an inner circumferential face of the centrifugally cast firstcopper end ring having a plurality of cooling fins distributed about theinner circumferential face, each of the plurality of cooling finsextending radially toward the central axial bore; a centrifugally castsecond copper end ring that electrically and mechanically couples eachof the plurality of copper bars proximate the second end surface of therotor lamination stack; an interior face of the centrifugally castsecond copper end ring having a plurality of recesses to couple with theplurality of copper bars; an exterior face of the centrifugally castsecond copper end ring having an entirely solid surface; an exteriorsurface of the second intermediary end ring directly contacts theinterior face of the centrifugally cast second copper end ring; an innercircumferential face of the centrifugally cast second copper end ringhaving a plurality of cooling fins distributed about the innercircumferential face, each of the plurality of cooling fins extendingradially toward the central axial bore; and each of the centrifugallycast first copper end ring and the centrifugally cast second copper endring centrifugally casted with the plurality of copper bars insertedinto the plurality of rotor slots, the plurality of copper bars insertedinto the multiple rotor slots of the first intermediary end ring, andthe plurality of copper bars inserted into the multiple rotor slots ofthe second intermediary end ring.
 2. The rotor assembly of claim 1,comprising: the centrifugally cast first copper end ring and thecentrifugally cast second copper end ring comprising the plurality ofcooling fins, each of the plurality of cooling fins having a rectangularshape with rounded edges.
 3. The rotor assembly of claim 1, comprising:the first intermediary end ring and the second intermediary end ringfabricated from at least one of stainless steel or electric steel. 4.The rotor assembly of claim 1, comprising: each of the firstintermediary end ring and the second intermediary end ring has athickness ranging from 1 mm to 5 mm.
 5. The rotor assembly of claim 1,comprising: the rotor lamination stack has a height ranging from 100 mmto 155 mm.
 6. The rotor assembly of claim 1, comprising: each of theplurality of lamination discs has an outer diameter ranging from 132 mmto 155 mm.
 7. The rotor assembly of claim 1, comprising: the rotorlamination stack has a central axial bore diameter ranging from 40 mm to50 mm.
 8. The rotor assembly of claim 1, comprising: each of theplurality of rotor slots has a slot height ranging from 18 mm to 22 mm.9. The rotor assembly of claim 1, comprising: each of the plurality ofrotor slots has a tapered shape with a first end slot width ranging from1 mm to 2.5 mm and a second end slot width ranging from 2 mm to 5 mm.10. The rotor assembly of claim 1, comprising: each of the plurality ofcopper bars is fabricated from oxygen-free electrolytic copper.
 11. Anelectric vehicle, comprising: an induction motor to drive an electricvehicle, comprising: a motor shaft; a stator assembly; a rotor assembly,comprising: a rotor lamination stack having a cylindrical shape thatdefines a central axis, the rotor lamination stack terminates in a firstend surface and a second end surface, a central axial bore extends fromthe first end surface of the rotor lamination stack to the second endsurface of the rotor lamination stack; the rotor lamination stack has aplurality of lamination discs, each of the plurality of lamination discshaving a plurality of rotor slots; a plurality of copper bars disposedwithin the plurality of rotor slots, each of the plurality of copperbars extends beyond the first end surface of the rotor lamination stackand beyond the second end surface of the rotor lamination stack; a firstintermediary end ring disposed at the first end surface of the rotorlamination stack, the first intermediary end ring having multiple rotorslots; a second intermediary end ring disposed at the second end surfaceof the rotor lamination stack, the second intermediary end ring havingmultiple rotor slots; a centrifugally cast first copper end ring thatelectrically and mechanically couples each of the plurality of copperbars proximate the first end surface of the rotor lamination stack; aninterior face of the centrifugally cast first copper end ring having aplurality of recesses to couple with the plurality of copper bars; anexterior face of the centrifugally cast first copper end ring having anentirely solid surface; an exterior surface of the first intermediaryend ring directly contacts the interior face of the centrifugally castfirst copper end ring; an inner circumferential face of thecentrifugally cast first copper end ring having a plurality of coolingfins distributed about the inner circumferential face, each of theplurality of cooling fins extending radially toward the central axialbore; a centrifugally cast second copper end ring that electrically andmechanically couples each of the plurality of copper bars proximate thesecond end surface of the rotor lamination stack; an interior face ofthe centrifugally cast second copper end ring having a plurality ofrecesses to couple with the plurality of copper bars; an exterior faceof the centrifugally cast second copper end ring having an entirelysolid surface; an exterior surface of the second intermediary end ringdirectly contacts the interior face of the centrifugally cast secondcopper end ring; an inner circumferential face of the centrifugally castsecond copper end ring having a plurality of cooling fins distributedabout the inner circumferential face, each of the plurality of coolingfins extending radially toward the central axial bore; and each of thecentrifugally cast first copper end ring and the centrifugally castsecond copper end ring centrifugally casted with the plurality of copperbars inserted into the plurality of rotor slots, the plurality of copperbars inserted into the multiple rotor slots of the first intermediaryend ring, and the plurality of copper bars inserted into the multiplerotor slots of the second intermediary end ring.